It has generally been known that molded articles of synthetic resins such as polyvinyl chloride, a polyethylene and an ABS resin, when used out of doors for a long period of time, are affected by sunrays such as ultraviolet rays, heat rays, etc., and a decline in their mechanical strength or a change in their color is caused thereby. In order to prevent these phenomena, there have been used various ultraviolet ray stabilizers of the benzophenone, benzotriazole, benzoate or piperidine series. Out of these ultraviolet ray stabilizers, the compounds having piperidyl groups, i.e. the so-called hindered amine-type ultraviolet ray stabilizers have been universally used for synthetic resins because of their excellent property of stabilizing ultraviolet rays, and there has been extensively made a study of development and application thereof.
It has been known, however, that when compounds having piperidyl groups per se are singly blended with synthetic resins as an ultraviolet ray stabilizer, the activity of the piperidyl groups is imparted by substances contained in said resins and detrimental to the piperidyl groups. As the origin of such substances detrimental to the piperidyl groups, there may be mentioned, for example, catalyst residues at the time of polymerization of said resins, various heat stabilizers for imparting heat stability at the time of processing at high temperatures, halogen-containing resins which per se have detrimental halogens, synthetic resins having fire retardants of the halogen series blended therewith, etc.
Compound having piperidyl groups are affected in some way or other by such substances as above contained in synthetic resins and at the time of processing at high temperatures, and there has been observed a decline in the effect of blending.